A comparison of ventilation strategies for the use of high-frequency oscillatory ventilation in the treatment of hyaline membrane disease.

To assess the efficacy of high frequency oscillatory ventilation (HFOV) in the management of infants with hyaline membrane disease (HMD), we compared two HFOV strategies with conventional positive pressure ventilation with positive end expiratory pressure (PPV) for 24 h in premature baboons (140 d gestation). Three out of 14 PPV, five out of five HFOV-E (begun at birth; 15 Hz; I:E 1:2), and none of 10 HFOV-L (begun after 3 h PPV; 10 Hz; I:E 1:2) were killed at 24 h for morphologic examination. Physiologic (Paw, Pa/AO2, IO2, B.P., pulse, blood gases) data on all animals in each group were assessed at each 3 h interval and over time. Intergroup differences in radiographs at 0 and 24 h and in morphology were quantitatively assessed by comparison with a panel of standards. All animals had radiographic HMD. Initial Paw was set higher with HFOV-E (16.8) than PPV or HFOV-L (14.1, 14.1). PPV baboons required increasing Paw to maintain constant Pa/AO2. Six out of 14 PPV animals developed airleak and three out of three had morphologic HMD. In contrast Pa/AO2 was higher in both HFOV groups at lower Paw by 24 h. None of 15 HFOV animals developed airleak. HFOV-E lungs had dramatic differences in morphology with uniform saccular opening and decreased edema and hyaline membranes compared to PPV. HFOV-L had less dramatic effects because of lower Paw and delayed application. Early use of HFOV at a high Paw favorably alters the course of HMD. Unless closely monitored, this strategy results in lung overinflation which may adversely affect venous return and cardiac output.